245 



even without previous enlargement and divisions of the cells 

 oonceraed. Parenahymntie excrescences of Solanura tuberosma 

 may he produced (according to Vochting's experiments) even 

 without any deposition in them of the usaal starch masses. 

 On the other hand, there e.3»e many oases, In which it is found 

 that abundant quantities of starch hcve been accumulated, with- 

 out any preceding formrtion of any excrescence whsttever ©to. 



It has not yet "been proved experimentally that all pro- 

 cesses actually oonre oted with one another in normal develop- 

 ment, 90 far as tine and place are concerned, can aasdiv their 

 "IndepdBAenoe" under suitable conditions and cp.n ooour indeptn*- 

 dent of those other processes v/ith which they seem to be com- 

 bined normally. Yet the actual material at hond JastifieS even 

 now the assumption that all processes of division should be 

 termed "independent" in the meaning' here explained, The capa- 

 (286) city for certain formative and differentiating processes id de* 

 termined. to be sure, by the speaial qualities of the aytoplasm 

 of the diffeiient plant varieties, The combination in space, 

 however, £?nd the sdnuenoe, in which we find the Separate pro- 

 cesses enacted in a normal course, tnay be understood as caused 

 by the influence of all tfffeotlve "internal" and "external" 

 fadtors, the majority ef whioh are evidently still withheld from 

 our knowledge. 



1 



Klebs-^ proved for the lov/er organisms. In the growth of 



which relatively few formrt^ve processes of division are re- 

 peated, that the oom]^lnatlon of these takes place quite differ- 

 ently under ohf.nging conditions of life and can be jsodified ex- 

 perimentally at pleasure. Thrt in higher plants only the incom- 

 pleteness of o\ir knowledge and our methods of experimentation 

 prevent the carrying through of similar experiments Is attested 

 to by the results of pathological plant anatoriy/ 



It is now desirable $o approach in still another way the 

 point treated here. 



If we compare the cells of abnormal tissues vrith those of 

 normal ones, we will find either complete correspondence (hom- 

 oeoplasias) or more cr less striking differences , The variation 

 of individual cells from the norrapl is on^y moderate when the 

 individual cells in one or more ways resemble the undeveloped 

 elements of normal tissues (hypoplasias and many kataplasmas); 

 On the other hhnd, the differences are often very mftisfeed in 

 metaplasia, in prosoplastic hypertrophy and especially in proso- 

 plasmatic galls. The diversity of abnormal cells brings up the 

 question, whether a plant under abnormal conditions can develop 

 other kinds and forms of cells than those which compose the 

 normally developed plant bo4y,- whether the same normal kinds 

 •f cells are always repeated in the pros ©plasmatic galls, in 

 new and "abnormal" arrangements and combinations. 



This question has always been repeatedly afeked in the dis- 

 cussion of galls, the most striking of abnormal tissues, and 

 has been answered in different ways/ 



^ Beitr. z. Phys, d. Pf lanzenzelle . fuhinger tJntersuch. 

 1886, Bd. XI g. e^speclally p. 550; Bedlng* d. Portpflanz, bei ein- 

 Igen Algen u. pilaen, Jena 1896, and others. 



